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Bull. Southern California Acad. Sci. 

95(3), 1996, pp. 120-126 

© Southern California Academy of Sciences, 1996 

A New Freshwater Clingfish (Pisces: Gobiesocidae) from 
Baja California Sur, Mexico 

Hector Espinosa Perez and Jose Luis Castro-Aguirre 

Coleccidn Ictioldgica, Instituto de Biologia, UNAM, 

A.P. 70-153 Mexico 04510 D.F. 

Centro Interdisciplinario de Ciencias Marinas, LP.N. Departamento de 
Pesquerias y Biologfa Marina, A.P. 592 La Paz 23000 B.C.S. 

Abstract . — A new species of freshwater clingfish is described. The species differs 
from other known freshwater species of the genus Gobiesox by its morphometries, 
morphology, tongue position, insertion and number of teeth and by the closer 
position of the anus to the anal fin. This is the seventh known freshwater species 
of clingfish of the genus in North America, the first in the Nearctic and the second 
endemic freshwater fish from the Peninsula of Baja California. 

Resumen. — Se describe una nueva especie de pez “cucharita” de agua dulce. La 
especie se diferencia de otras especies dulceacuicolas del genero Gobiesox por 
sus medidas morfometricas, morfologia, posicion de la lengua, la insercion y 
numero de dientes y por la posicion del ano mas cercano a la aleta anal. Esta es 
la septima especie conocida del genero en aguas dulces en Norteamerica, la pri- 
mera en la region neartica y la segunda especie endemica de la peninsula de Baja 

The family Gobiesocidae has a large geographic distribution and is composed 
of eight subfamilies (Briggs 1993). One subfamily, Gobiesocinae, includes nine 
genera and ca. 60 species distributed almost exclusively in tropical and subtropical 
waters of America (Briggs 1955). The most diverse genus in the subfamily is 
Gobiesox Lacepede, which contains a great proportion of species inhabiting rocky 
or coralline habitats in the neritic zone. There are some exclusively freshwater 
species that may be classified as the vicarious or complementary component of 
Myers (1963). These include the Western American species G. potamius Briggs, 
G. juradoensis Fowler, G. fulvus Meek, G. mexicanus Briggs and Miller, G. flu- 
viatilis Briggs and Miller, the new species described here, and the Eastern North 
American G. nudiis (Linnaeus). 

In Mexican freshwater, two species, G. fliiviatilis and G. mexicanus, have been 
reported (Briggs and Miller 1960; Burr and Buth 1977; Espinosa Perez et al. 
1988). Two other species, G. strumosus Cope and G. adiistus Jordan and Gilbert, 
have been collected in brackish water in the estuaries of Rio Tuxpan, Veracruz, 
and coastal lagoons and tidal flats of Sonora, Sinaloa, and Nayarit (Castro-Aguirre 

The specimens that are the basis for the description of the new species were 
collected during a biological field trip near the southern portion of the Sierra de 
la Giganta, Baja California Sur, close to the town of Pocitas (approx. 100 km 
north of La Paz). This finding is biogeographically interesting, and provides ev- 




idence for potential speciation patterns in the genus. In particular, it offers some 
clues to the origin and adaptation of the freshwater fish fauna of Baja California 
Peninsula, which has a very low diversity (Follett 1961). Fundulus lima Vaillant 
and the new gobiesocid are the only reported endemic freshwater fishes to Baja 


Counts and measurements follow Briggs (1955) and Briggs and Miller (1960). 
Measurements were made using dial calipers and presented as thousandths of 
standard length (SL). IBUNAM-P is the abbreviation of the Instituto de Biologia, 
UNAM fish collection, formerly UNAM in Leviton et al. (1985). 


Gobies ox juniperoserrai n. sp. (Fig. 1). 

Holotype. — IBUNAM-P 7606, male 105.2 mm SL, Las Pocitas (Poza del 
Vado), Baja California Sur, Mexico, collected by Paulino Perez and party, 12 May 

Paratypes, — IBUNAM-P 7607 (2) collected with the holotype, which are 
cleared and stained (67.4-98.2 mm SL). 

Diagnosis. — A Gobiesox with poor development of head papillae and smooth 
margin of upper lip. Lower jaw without accessory incisor-like teeth and two rows 
of flat incisor-like teeth. Tongue completely adhered to mouth floor. Origin of 
dorsal fin closer to base of caudal fin than to upper part of base of pectoral fin. 
Anus much closer to base of anal fin than to pelvic disc margin. The three spec- 
imens have head contained 2. 2-2. 7 times in SL, and 27 vertebrae. Each part of 
region C of the disc has 5-6 longitudinal rows of papillae and 7-8 rows cross 
with region A of the disc. Dorsal fin rays 13 (13-14), anal fin rays 7 (7-8), 
pectorals fin rays 22 (22-24), and caudal fin rays 13 (13-14). 

Description . — Depressed body, depth 5. 3-5. 6 in standard length; short caudal 
peduncle, least depth 0.6-0. 7 in its length. Head very broad, width 2. 2-2. 7 and 
length 2. 3-2. 6 in SL. Eye 2. 5-3. 2 in bony interorbital space, and 6. 7-7. 7 in head 
length. Short and rounded snout, 2. 9-3. 2 in head length. Posterior nostril tubular, 
located at anterior edge of eye; anterior nostril tubular, provided with bilobed 
dermal flap. Upper jaw anteriorly with 5-6 pairs of incisor-like teeth with rounded 
edges; posteriorly on each side, there are canine-like teeth with flat or slightly 
rounded edges; inner row with irregularly small conical teeth of variable size. 
Lower jaw with two rows of teeth, anterior row with 5-6 pairs of compressed, 
flat incisor-like teeth followed by a single series of 8 conical canine like-teeth 
without accessory incisor-like teeth. The second row is a patch of very small 
conical teeth behind the two frontal pair of incisors (Fig. 2a-b). The tongue is 
completely adhered to the floor of the mouth. Five shallow and small rakers on 
the posteriormost gill arch. Upper attachment of gill membrane opposed to the 
4th pectoral fin ray. Subopercular spine weak and small, almost inperceptible. 
Postdorsal-caudal distance 1.8 in dorsal length. Length of disc is 2.9 in standard 
length. Anus is much closer to anal fin origin, and the urogenital papilla is formed 
as a single structure (fig. 2c). 

Coloration. — In alcohol, the dorsal and lateral sides are evenly medium brown, 
with small black spots scattered on the body. The dorsal, anal and caudal fins are 



Fig. 1. Holotype of Gobiesox juniperoserra lateral, dorsal and ventral view. 

brown except in their bases and two caudal pale bars. Ventral surface of body is 
translucent; the area near the vent is almost colorless. 

Habitat . — The types were collected in a small semipermanent creek called Po- 
zas del Vado. It is located at the lower end (SW) of Sierra La Giganta, B.C.S. 




Fig. 2. Left dentary a) lateral and b) dorsal view, c) Urogenital papillae. 



(Fig. 3). The average height above sea level varies from 30 to 60 m. This area 
is located between 24°28' and 24°52'N and 110^49' and 111°49'W. Climate is 
extreme, being the most arid of the semidry climates of the Peninsula, with a 
mean annual temperature ranging from 20 to 22"^C, and rainy seasons, in summer 
and winter. 

The hydrologic basin of the area is reduced to a few small natural pools (=po- 
zas, origin of the generic name of the region). The creeks are located along two 
canyons that merge. Those located in the southern region merge directly or in- 
directly with a small river that goes to the Flor de Malva estuary, opening to the 
Pacific. Rivers to the north and west of the Mesa de Irai plain are joined with 
other small channels that occasionally reach the Punta Chale estuary opening into 
Bahia Almejas, at the lagoon system of Bahia Magdalena, Baja California Sur. 

The Pozas del Vado are a series of ponds watered by small springs. Their 
diameters range from two to six meters, with a depth from 20 to 50 cm. They 
remain isolated during the dry season, but become interconnected at the onset of 
the rains and give rise to the two rivers mentioned above. This ecological setting 
can be compared to some biotopes located in mainland Mexico, particularly in 
the states of Jalisco, Michoacan, Guerrero, and Oaxaca. 

The floor of these water bodies is composed of sand, gravel, and rocks. Toward 
the edges of the ponds, due to accumulation and decomposition of organic matter 
small muddy beaches are formed. Large rounded rocks of rhyolithic material 
located in the rivers are common. 

The aquatic vegetation collected in this locality is represented by the algae 



Chara sp., and the monocotyledon Potamogeton sp. The fresh water fauna is not 
diverse. To date, larvae of insects like odonates and corixids, and some amphib- 
ians, probably Bufo marinus, have been identified. Other organisms include fresh- 
water shrimps (Macrobrachium americanus, Palaemon sp.) and fishes (Agonos- 
tornus rnonticola, Gobiomorus maculatus, Awaous trasandeanus, Eleotris picta^ 
and the exotic Poecilia reticulata). 

Etymology: The name juniperoserrai is for Fray Junipero Serra, Jesuit mis- 
sionary, evangelizer, and explorer of the Alta and Baja California region during 
the Colonial epoch. 

Key to the Mexican freshwater species of Gobiesox 

1. Anus closer to anal fin origin than to rear margin of disc; 13 (13-14) 

rays in dorsal fin; lower jaw with two rows of incisor like teeth and with 
out accessories incisor-like teeth; tongue adhered to the floor of the 
mouth G. juniperoserrai 

- Anus midway or closer to rear margin of disc than to anal fin origin; 

tongue not adhered to the floor of the mouth 2 

2. Anus midway between rear margin of disc and anal fin origin; lower jaw 

with a single row of incisor-like teeth; 10 (9-10) rays in dorsal fin and 8 
(7-9) rays in anal fin G. fluviatilis 

- Anus closer to rear margin of disc than to anal fin; lower jaw with several 
rows of incisor-like teeth and accessories incisor-like teeth in front row; 

12 (11-12) rays in dorsal fin and 7 (6-8) rays in anal fin G. mexicanus 


The discovery of Gobiesox juniperoserrai in fresh waters of the southern part 
of Baja California Peninsula is important from a biogeographic point of view. 
The closest relative of G. juniperoserrai based on morphological and morpho- 
metric characteristics seems to be G. mexicanus, distributed from Rio Cuitzmala, 
Jalisco, south to the Tehuantepec Isthmus, Oaxaca. This distributional pattern 
supports the hypothesis of Castro- Aguirre and Torres-Orozco (1993), who sug- 
gested that the fish fauna of the southern part of the Sierra de la Giganta has a 
great affinity with the fresh water fish fauna of the southern part of Jalisco and 
Michoacan. Hausback (1984) has argued that this geographic area of continental 
Mexico corresponds geologically with the southern part of the Baja California 

The origin of Gobiesox juniperoserrai could therefore be hypothesized as the 
result of allopatric processes began with the drifting of the Peninsula toward the 
northwest, perhaps during Miocene or Pliocene time. The geographic isolation of 
the populations, and the time elapsed may be the main factors giving rise to the 
new species from a relative close to G. mexicanus. 

Besides the morphological differences between G. fluviatilis, G. mexicanus, and 
G. juniperoserrai, there are important distinctions in their habitat preferences. 
Gobiesox fluviatilis is an important component of the mountain rivers, especially 
those located between 750 and 1000 meters above sea level (Briggs and Miller 
1960; Burr and Buth 1977). 

Although the three species belong to the complementary fish component of 



Myers (1951, 1963), it is evident that G. mexicanus may be included in the 
Neotropical fish fauna, whereas G. fluviatilis could be cataloged as a nearctic 
element. Gobiesox juniperoserrai represents, therefore, a northern species with 
Neotropical ancestry. 


We are indebted to P. Perez for collecting the specimens. W. A. Bussing, R. R. 
Miller and D. W. Nelson loaned specimens and x-rays for comparing the new 
species. Photographs are by H. Hernandez. 

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Accepted for publication 1 February 1996.